But the final quality has less to do with the encoding settings, than with the content itself (this example has very little motion , except for the end and has good lighting, shot well, little noise, shallow DoF) . All those factors make it easier to compress. If you had different content that had lots of motion , noise, it would "fall apart" at that bitrate . Long GOP video compression works by coding and storing the differences between frames - when there are few differences, the filesize required for a certain level of "quality" is much lower

It's just the vimeo encoder. You can see the x264 settings used if you download the video. Most of it looks like the default "medium" settings , with 3 sec gop and vbv settings